The amount of a given metal salt which can be incorporated into an oral care product is often limited as a result of unfavorable effects on the sensory experience of the user, for example, astringency, taste and mouth feel. Zinc is a particularly difficult metal ion to incorporate into oral care compositions, as the concentration at which it is effective as an antimicrobial agent is very close to the concentration at which it is unacceptably astringent.
These limits on metal salt concentration have made it difficult to deliver an effective amount of a metal ion to the soft and/or hard tissue of the oral cavity using an oral care composition. Embodiments of the present invention provide compositions which address, inter alia, this problem.
WO 2012/087288A2, incorporated herein by reference, has disclosed oral care compositions comprising combinations of metal salts, and in particular, combinations of insoluble zinc salts and soluble zinc salts. WO 2012/087288A2 includes in its disclosure combinations of zinc oxide and zinc citrate. However, this reference does not teach specific ratios of net zinc to net citrate, specific pH values, or a combination of zinc chloride and zinc citrate.